Has the carby been completely dismantled and cleaned (main jet and emulsion tube taken out ,removed the low speed jet. on the top of the carby , it's beneath the black cap.)
Fuel tap needs to be removed and cleaned ,check fuel flow with the fuel bowl removed ,clean needle and seat orifice.
You may need an ultrasonic cleaner but occasionally they still won't clean out and you can just buy a replacement carby for $17. with free postage.
